HELENA, Mont. (AP) — A judge has upheld the federal government's decision not to designate Montana's Arctic grayling as a threatened or endangered species.

U.S. District Judge Sam Haddon said in an order Friday that the U.S. Fish and Wildlife Service's 2014 decision was based on the best available science and considered all the factors required under the Endangered Species Act.

Environmentalists led by the Center for Biological Diversity sued for federal protections for the fish. They say it is threatened by warm waters and low stream flows.

The Fish and Wildlife Service determined in 2010 that Arctic grayling in Montana warranted federal protections, but that other species took precedence.

U.S. Department of Justice attorneys say 15 new Arctic grayling populations have been identified since then, and a successful landowner program has improved the fish's habitat.